Longboard convex tail

I’ve been making a few boards in the UK, and I want to make myself a longboard. I’ve noticed most longboards have a convex v section in the rear quarter. Does this help to turn the board? Can anyone give me some advice? Thanks, Mark

A vee in the tail makes for a slightly looser more forgiving board. But too much vee will slow the board somewhat.

A vee in the tail makes for a slightly looser more forgiving board. But > too much vee will slow the board somewhat. So what are we talking - about 1/8 inch from rail to center? Also, how far forward of the fin box would you start the vee?